1. Field of the Invention
The present invention relates to a semiconductor device and a method of manufacturing the same and, more particularly, to preventing the diffusion of the copper of the copper wiring layer.
2. Description of the Related Art
In recent years, in order to increase the operational speed of a semiconductor element such as a LSI, etc., an insulating film having a low dielectric constant (referred to as a “low dielectric constant film” hereinafter) is formed on the copper wiring layer as the interlayer insulating film. In this structure, the low dielectric constant film is formed on the copper wiring layer as an interlayer insulating film, and then a via hole is formed in this low dielectric constant film to expose the copper wiring layer. In forming this via hole, a block insulating film is formed on the copper wiring layer in advance, and then the interlayer insulating film is formed on this block insulating film. The block insulating film serves as an etching stopper film when etching the interlayer insulating film. The block insulating serves also as a copper diffusion preventing film, which prevents copper contained in the copper wiring layer from diffusing into the interlayer insulating film.
In the prior art, a silicon nitride film (referred to as “SiN film” hereinafter), which is superior in preventing the copper diffusion, is used for the block insulating film.
SiN film, however, has a problem in that it lowers the operational speed of the semiconductor device due to its high dielectric constant (about 7).
Low dielectric constant films, as a substitute for the SiN film, are also known to be used for the block insulating film. These low dielectric constant films are formed using a CVD method (Chemical Vapor Deposition method), and the reaction gases for this method consist of methylsilane (Si(CH3)4) and CH4 or organic silane and CH4. These methods, however, are problematic because a large number of Si—C bonds are formed in the low dielectric constant film. Since the Si—C bonds increase the leakage current in the film, the block film formed as above has the problem that the leakage current is large.